But It Is Unclear Whether Abdullah Gul Will Retire Or Seek a Second Term Against Recep Tayyip Erdogan

ISTANBUL—President Abdullah Gul ruled out speculation that he would swap posts with Prime Minister Recep Tayyip Erdogan in Turkey's August elections, signaling a growing split between the two old allies and injecting new uncertainty into the political process.

The development could have weighty implications for the arc of Turkey's leadership after the first election in which voters will directly choose their president, an office Mr....